This invention relates to door closer apparatus in general and more particularly relates to surface mounted door closer apparatus that are resistant to vandalism.
Wall openings through which people enter and exit secured and/or limited access areas of buildings are normally provided with hinged doors that are closed by adjustable and variable spring loaded mechanisms. Examples of suitable mechanisms are door closer units that include spring loaded mechanisms of the type disclosed in U.S. Pat. No. 3,911,527 issued Oct. 14, 1975 to T. R. Lasier for a Spring Adjustment Mechanism and in U.S. Pat. No. 4,019,220 issued Apr. 26, 1977 to S. Lieberman for a Piston Assembly for Door Closer. Such closer units function to bias a door closed and to control the speed at which the door moves to its closed position.
A closer unit and its associated linkage are connected between a door and the door frame or jamb at the wall opening that is closed by the door. When the closer unit is mounted on the door, one end of the linkage is pivotally connected to the frame, and when the closer unit is mounted on the frame one end of the linkage is pivotally connected to the door.
Generally a closer unit will move the door slower as it approaches its closed position and when at a nearly closed position a surge of energy is released to continue moving the door in its closing direction. This surge of energy overcomes forces of a latching mechanism that holds the door locked in its fully closed position.
Door closer units and their associate linkages are often subjected to vandalism. Sometimes the vandals steal the closer units, but more often the vandals are seeking immediate entrance to the limited access area for illegal purposes. Once vandals have opened a door to a secured area, they take steps to insure that the door does not close fully and become latched closed. This can be accomplished by disabling the linkage, as by distorting elements thereof to the extent that the closer apparatus is unable to move the door to its fully closed position.